16840 - EVAP System: Very Small Leak Detected

[axalott]

Anyone familiar with this code? I changed the EVAP Purge Valve, wipe out the error code but the error came back. Appreciate all the help.

16840 - EVAP System: Very Small Leak Detected
P0456 - 002 - Lower Limit Exceeded - MIL ON

[cbirgl]

Leak in the system somewhere. Could even be from loose gas cap. You should do a smoke test or there are a few other tricks to finding it out.

[axalott]

Thanks... Initially I thought it would be the EVAP Purge Valve so I changed it but the code returned, then I changed the rubber seal on the gas cap and the code returned again. What are some tricks in testing the vacum lines? .. other than smoke machine.

[cbirgl]

If you have a vag-com you can block the evap lines and run the test. You start from the farthest point from the pump and move closer to it. As you move the blockage back, eventually the test will pass. If it passes, the leak is after the blockage.

[ein]

Starting fluid test...:mrgreen: make sure you smoke em if you've got em. :wink:

[MTV2002]

http://forums.audiworld.com/showthread.php?t=1595413 try this out, its for an audi s4 but the concepts are the same. smoke testing wont work because the charcoal canister will absorb the smoke and you wont see anything. hope that helps

[cbirgl]

http://forums.audiworld.com/showthread.php?t=1595413 try this out, its for an audi s4 but the concepts are the same. smoke testing wont work because the charcoal canister will absorb the smoke and you wont see anything. hope that helps

Smoke testing does work, and in fact, some of the vehicles have a port for that from the factory. Others use an adapter on the fuel cap

[axalott]

Thanks to all, it turned out that when I changed my fuel pumps I reversed two of the gas lines. I was getting stalls when reaching 1/4 tank of gas so I felt like something was weird with the gas. When I removed the sending units and looked inside, one tank was completely empty and the other was full so looking at the lines I realized I f-up. Im just glad I didn't mess up anything else, I actually drove about 2k miles with the lines reversed but it seems fine now.


Lesson learned.. If a car has multiple fuel pumps, change one at a time or better yet, label all the lines otherwise you will scratch your head until it hurts.

[cbirgl]

Yea I think I was replying in your club touareg thread as well. Glad you got it sorted out!